The present invention relates to a stencil printer capable of printing a multicolor image on a paper or similar recording medium with a plurality of print drums.
A multicolor stencil printer of the type including a plurality of parallel print drums arranged in a direction of paper conveyance is conventional and taught in, e.g., Japanese Patent Laid-Open Publication No. 10-297073. In this type of printer, pressing members each are movable into and out of contact with a particular print drum. When each pressing member is pressed against the associated print drum with the intermediary of a paper or similar recording medium, the rotation of the print drum is transferred to a paper. As a result, an image is printed on the paper being conveyed by the print drum. The paper with the image is driven out to a print tray located at the most downstream side of the printer.
A problem with the above multicolor stencil printer is that even in a monocolor print mode, all the pressing members are pressed against the associated print drums and cause ink to be transferred from unused print drums to the corresponding pressing members and a paper. To solve this problem, it has been customary to wrap non-perforated stencils around the unused print drums and thereby prevent ink from depositing on the associated pressing members and paper. This is, however, undesirable from the cost standpoint because non-perforated stencils must be wrapped around the unused print drums every time the monocolor print mode is selected. Another problem is that because the print tray is located at the most downstream side in the direction of paper conveyance, sufficient conveying forces do not act on the paper when the pressing members are released from the print drums, resulting in defective paper conveyance.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 1-290489, 3-55276, 6-32038, 7-17121, 10-305649, and 11-34467.
It is therefore an object of the present invention to provide a multicolor stencil printer which does not require non-perforated stencils around unused print drums and thereby reducing the print cost.
It is another object of the present invention to provide a multicolor stencil printer capable of exerting a sufficient conveying force on a paper even when a pressing member does not press it and thereby obviating defective paper conveyance.
A multicolor stencil printer of the present invention includes a plurality of print drums each storing ink of particular color therein, a plurality of pressing members each being movable into and out of contact with a particular print drum, and a plurality of holding devices each being assigned to a particular pressing member. In a color selective print mode in which the print drums and pressing members selectively cooperate to nip a recording medium for printing an image, the holding devices associated with the pressing members unused in the above mode hold the pressing members at positions spaced from the associated print drums.